Six element petzval-type projection lens



350-464 SR I SEARCH ROOM June 30, 1970 P. RUBEN 3,517,985-

S IX ELEMENT PETZVAL-TYPE PROJECTION LENS Filed Jan. 23, 1968 .05%/' o+.05%f -./%*F o o PAUL RUBEN v INVENTOR.

BY a

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ATTORNEYS I United States Patent Olfice 3,517,985 Patented June 30, 1970s,s17,9ss SIX ELEMENT PETZVALS-TYPE PROJECTION.

LEN Paul L. Ruben, Penfield, N.Y., assignor to Eastman Kodak Company,Rochester, N.Y., a corporation of New element between the doublets isbiconvex and located I exceptionally close to the rearmost doublet toreduce which the negative element in the rear doublet is exceptionallythick to reduce curvature of field together with Jersey p sphericalaberration. Glasses having high refractivein- Filed g -i i dexes areused in all elements except the positive ele-' U s C] 'g' 8 Claims mentlocated between the doublets. These high refractive indexes permit theselection of surface curvatures to reduce spherical aberration at highapertures. THE The above described features are provided according u tothe invention in improved modified Petzval lenses modlfied Petzvfil lensdlsclosed colhpnsmg two comprising two airspaced doublets, a biconvexpositive Wldely Separated all'spaced doublets a blconvex element betweenthe doublets and a negative field flatmentlocatcdhet the doublets, and afield flattening 15 tening element behind the rearmost doublet, whereinthe negatlve element behmd the real'most doublet parameters of the lenselements are substantially within the following ranges of values, inwhich the lens elements are numbered from the front (i.e. the long con-BACKGROUND OF THE INVENTION jugate side). N is the index of refractionof each lens This invention relates to projection lenses and parelemente the D line of the p th V e index ticularly to highly correctedmodifications of the wellh p l and R, T and 3 refer reSPeetl Ve1Y t0 theknown Petzva1 type 1 radii of curvature of the lens surfaces, thethlcknesses of petzvaptype lenses' usually comprise two id l Sepa. thelens elements and the airspaces between the elements, rated doublets,which are either cemented or slightly airnumbered y Subscript fromf1'0ht to rear:

Equivalent Focal Length=l00 mm. f/LO Thlcknesses and Lens N V Radll(mm.) spacings (mrm) Rl=96.13 to 114.3 I 1.611 to 1.713 53.8to58.8 T=22.7to28.6

' Rz=762.5 to 1l26 sl=1l.5 to 19.7 R =-137.1to 154.8 n 1.672 to 1.72828.3 to 32.2 T, =11 4 o 22,2

. R4=232 to 1612 s2=41.5 to 53.2 17' e4 0 to 64 5 RES; to 'r 4 to as 1III 1.516 to 1.5 R= 1960to 3251 a s =1.79 to 2.33 a 53 s to 58 s R7=6M2to T a 82 to 13 0 I 1 IV 1 to} 7 Rs=+1816 to -2s45 S4=LO8 to 2.22 R=-145.4 to 189.6 V 1.717150 1.755 27.5 to 29.5 T =22.5to 33.4

R =192.6 to 340.5

. s5=3.14 to 5.05 R 1=50.70 to 71-00 VI 1.717 to 1.755 27.5 to 29.5Ts=2.50to 3.64

spaced. They cover a relatively narrow angular field and Mo t Of t aboveranges h t parately distinguish are usually not particularly wellcorrected for astigma- Over the P e lhVehtlOh 15 the combinatism orcurvature f fi 1d However, h give good tion of parameters which definemodifications of a well- 7 resolution at high aperture. Because of thecurvature of knovyn yp of s- The Important characteristics f the field,a field flattener is usually added to such systhe m en are the values oralrspaees 1 3 e 4 terns immediately in front of the focal plane. It isalso and the thlekness 5 of element The sepafatlohesl quite common toinclude a positive element between the and 4 hetween the dollhlets arelarger than 111 P two doublets for increased apertures. Such modified tlenses of this yp 1 being greater h hand o. systems, in which thedoublets are airspaced, have been bemg vgreater than Element n 15located Very found to produce satisfactory resolution for projectionclose to the rear doublet, such that S is less than .02F purposes atapertures as large as f/ 1.0. An example of which is smaller than thecorresponding airspace 1n prlor Such a lens is disclosed i Us N3,320,016 i art lenses. Lens Element Vls thicker than .2F as comwhich af/1.0 modified Petzval lens is disclosed having pa wltll orsmallerleerrespendmg thleknesses astigmatism of less than 4% of thefocal length. dlselosed 111 the Prlor h SUMMARY OF THE TIONBRIEFDESCRIPTION OF THE DRAWINGS The object of the present invention isto provide im- Preferred embodimeants of the invention are disclosedproved lenses of the modified Petzval type operating at below hreference t0 the drawings: f/ 1.0 which are particularly well correctedfor field FIG. 1 illustrates a lengs system incorporating aprecurvature, as well as for spherical, comatic, chromatic rred embomeilt Of t e Invention; and astigmatic aberrations and for distortion.FIG. 2 comprises a set of correction curves for the According to thepresent invention, modified Petzval 'lens disclosed in Example l belowshowing the lenses of the type described above are provided, inspherical aberration curves for the C, D and F lines of the spectrum,(B) the curves for sagittal and tangential astigmatism, and (C) thecurve for distortion; and

the elements of each doub 1et FIG. 3 comprises a similar set ofcorrection curves for the lens disclosed in-Example 2 below.

DESCRIPTION OF THE PREFERRED EMBODIMENT of the lens. Elements I, III andIV are biconvex, and elements II and V are both biconcave. The fieldflattening element VI is concave-piano. Although element IV in thisembodiment is biconvex, it can be positive meniscus element, as inExample VI 'below. In addition, element VI can be'biconcave, as inExample VII.

Numerical data for constructing typical projection lenses according tothe invention as outlined above is given in the following sevenexamples:

EXAMPLE 1 Equivalent Focal Length=100 mm. f/1.0

Thieknesses and Lens N V Radn (mm.) spacings (1mm) R1= 107.3 I 1. 71353. 9 T1=27.6

81 17.1 Rs= 154.3 II 1.728 28.3 T =11.4

Sz=56. 8 R =5L24 III 1. 516 64. 0 T =30.0

S3=2.27 R7=63.48 IV 1 713 53. 9 T =10.7

S4=1.99 R9 1.51.9 V 1. 755 27. 5 T =22.5

S =4.95 R -50.70 VI 1. 755 27. 5 Ta=3.18

R12= Plano EXAMPLE 2 Equivalent Focal Length= 100 mm. 17 1.0

Thicknesses and Lens N V Radix (mm.) spacings (mm.)

S1 19.1 Ra= --153.3 II 1. 728 28. 4 Tg=22. 2

S =47.5 R 51.55 III 1. 517 64. 2 T;=33.7 Rt= -247.9

Sa=1.79 R =63.22 IV 1. 713 53. 8 T =8.82

S 1.96 Ra= -145.4 V 1.755 27. 6 T =24.2

, S =3.68 R11= 53.03 VI 1. 755 27. 6 Ts=3.54

' R12= Plano As shown by the curves in FIGS. 2 and 3, the lensesdescribed above in Examples 1 and 2, respectively, are corrected to sucha degree that spherical abberation for the D line of the spectrum isless than 0.1 percent of the focal length, the sagittal and tangentialfields vary less than 0.15 percent of the focal length and distortion isless than 2 percent.

EXAMPLE 3 Equivalent Focal Length=100 mm. f/1.0

Thicknesses Lens ND V Radix (mm.) and spacings 5 (mm.)

S 13. 0 1O Ra 137. 1

II 1. 672. 32. 2 T2=11. 4

Sz=41. 5 R 66. 13 III 1. 516 64. 0 T =26. 4 R 196. 0 S 2 7 IV 1. 613 58.6 T4=13. 0

S4=1. 35 R -149. 6 V 1. 717 29. 5 T =33. 4

R11 52. 49 VI 1. 717 29. 5 Ta=3. 18

R Plano EXAMPLE 4 Equivalent Focal Length=100 mm. f/ILO Thicknesses LensND V Radii (mm.) and spacings R =97. 88 I 1.611 58.8 T1=27.4 R2 ---885.6

R3 I4I. 4 II 1. 672 32. 0 Tz=12. 7

Y S; 44. 3 R5=64. 24 40 III -1. 517 64. 5 T3=25.9

S;=2. 27 R =74. 1o IV 1. 611 58.8 T4=12.8

S4= 1. 23 R 153. 7 V 1.720 29.3 T5=31.9

S5=5. 05 R 5 2. 07 VI 1. 720 29. 3 Ta=3. 18

. R z=Plano 7 EXAMPLE 5 Equivalent Focal Length=100 mm. f/1.0

Thicknesses Lens N V Radii (mm.) and spacings R1= I05. 6 I 1. 697 56.2T1=28. 6

R -154. 8' II 1. 720 29. 3 T2=1L 4 S2=52. 2 p R =54. 1s 60 m 1.511 64.5T.=3o.s

S3=2. 27 R1,=64. 14 IV 1. 697 56. 2 T4=10. 9

Rg= 1560 7 R 15 G S4=2. 22

Q: 0. 0 V 1. 751 27. 8 'I5=24. l Rm=340. 5

S5 4. R11= 54. 93 V I 1. 751 27. 8 Tn=3. 18

R1z=Plano 75 EXAMPLE 6 Equivalent Focal Length=100 mm. f/1.0

I Thicknesses -Lens N1) V Radtl (mm.) and spacings R 114. 3 I. 1. 69756. 2 T =25. 7

S1=19. 7 Ra= 151. 6 II 1. 720 29. 3 Tz= 19. 6

S2= 52. 2 R5=52. 45 III 1. 517 64. 5 '1;=33. 5

S3=2. 04 R =61. 42 IV 1. 697 56. 2 T =8. 94

S4=2. 07 Rg= 149. 4 V 1. 751 27. 8 T =25. 8

S5=4. 19 Ru= 53. 85 VI l. 751 27. 8 Tg=2. 50

R z=Plano EXAMPLE 7 Equivalent Focal Length= 100 mm. f/1.0

' 'lhlclmesses and Lens Ni) V Radll (mm.) spacings (mm.)

R1=109.6 I 1. 611 58. 8 T =22.7

Sl= 19. 6 R3: 147.1 II 1. 720 29. 3 T 11.4

R4= 1612 Sz=63. 2

R5=60.19 III 1. 517 64. 6 T;=25. 4

S3=2.33 R1=70.71 IV 1. 697 56. 2 T4= 12.9

S4= 1.08 v R9= l89.6 V l. 751 27. 8 T 26.6

$5=3.14 R 71.00 VI 1. 751 27. 8 T =3.64

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be efiected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims. I

I claim:

1. A lens having an equivalent focal length of 100 mm.

elements and the axial spacings between the lens elements, 7 I

numbered by subscript from front to rear:

Lens N V Radii (mm.) Thielrnesses .and

spacings (mm pp) R1= 107.3 I 1.713 53.9 Tl=27.6

S1= 17.1 R 154.3 II 1. 728 28. 3 T =11. 4

Sz= 56. 8 R5=5L24 III 1. 516 64. 0 T =30.0

' S3= 2.27 R7=63.48 IV 1. 713 53. 9 T 10.7

S4=1.99 R 151.9 V 1. 755 27. 5 T =22.5

S =4.95 Ru= 50.70 VI 1.755 27. 5 T =3.18

R =Plano 2. A lens having an equivalent focal length of mm. comprisingsix airspaced elements having substantially the followingcharacteristics in which the lens elements are numbered from the front,N is the index of refraction for the D line of the spectrum, V is theindex of dispersion, and R, T and S refer respectively to the radii ofcurvature of the lens surfaces, the axial thicknesses of the lenselements and the axial spacings between the lens elements, numbered bysubscript from front to rear:

Lens N D V Radli (mm.) Thieknesses and spacings (mm.)

R1=112.0 I 1. 713 53. 8 T =26.3

S1= 19.1 R3 265.4 II 1. 728 28.4 T =22. 2

R 265.4 S =47.5 R5=5L55 III 1. 517 64. 2 T =33.7

' S3= 1.79 R1=63.22 IV 1. 713 53. 8 '14=8.82 Ra=2313 Rn= 145.4 V 1. 75527. 6 T =24.2

S =3.68 R11= 53.03 VI 1. 755 27. 6 Ts=3.54

' R1 =PIan0 3. A lens having an equivalent focal length of 100 mm.comprising six airspaced elements having substantially the followingcharacteristics in which the lens elements are numbered from the front,N is the index of refraction for the D line of the spectrum, V is theindex of dispersion, and R, T and S refer respectively to the radii ofcurvature of the lens surfaces, the axial thicknesses of the ThlcknessesLens N,, V Radii (mm.) and spacings R =96. 13 I 1.613 58. 6 T1=26.3

S =13. R3 I37. 1

II 1. 672 32. 2 T2=11. 4

S2=41. 5 R =66. 13 III r 1.516 64.0 T3=26.4

S3=2. 27 R =73. 38 IV 1. 613 58. 6 T4=13.0

S4=1. 35 Rg= 149. 6 V 1.717 29.5 T =33.4

S5=4. 95 R 52. 49 VI 1. 717 29. 5 T 3. 18

Rn= Plano 4. A lens having an equivalent focal length of 100 mm.

comprising six airspaced elements having substantially the followingcharacteristics in which the lens elements are numbered from the front,N is the index of refraction for the D line of the spectrum, V is theindex of dis:

persion, and R, T and S refer respectively to the radii of I ThicknessesLens N, V Radil (mm.) and spacings R =97. 88 v I 1.611 58.8 T =27.4

' S =1L 5 R3 @141. 4 II 1. 672 32.0 Tz=l2. 7

R4=472. 4 I S2=44. 3

R5=64. 24 III. 1. 517 64. 5 T:=25. 9

S1=2. 27 R =74. 10 IV 1. 611 58. 8 'I4=12.8

S4=1. 23 Rp= 153. 7 V 1. 720 29. 3 Ts=31. 9

S5=5. 05 R 52. 07 VI 1. 720 29. 3 T =3. 18

R z=P1ano 5. A lens having an equivalent focal length of 100 mm.comprising six airspaced elements having substantially the followingcharacteristics in which the lens elements are numbered from the front,N is the index of refraction for the D line of the spectrum, V is theindex of dispersion, and R, T and S refer respectively to the radii ofcurvature of the lens surfaces, the axial thicknesses of the lenselements and the axial spacings between the lens elements, numbered bysubscript from front to rear:

6; A lens having an equivalent focal length of 100 mm. comprising sixairspaced elements having substantially the following characteristics inwhich the lens elements are numbered from the front, N is the index ofrefraction for the D line of the spectrum, V is the index of dispersion,and R, T and S refer respectively to the radii of curvature of the lenssurfaces, the axial thicknesses of the lens elements and the axialspacings between the lens elements, numbered by subscript from front torear:

' Thlcknesses Lens N, V Radii (mm.) and spacings R =114. 3 I 1. 697 56.2 T1=25. 7

S1=19. 7 R3: -151. 6 II 1. 720 29. 3 Ta=19. 6

S 52. 2 R5=52. 45 III 1. 517 64. 5 T3=33. 5

S3=2. 04 R7=61. 42 IV 1. 697 56. 2 T4.=8. 94

S4=2. 07 R9= 149. 4 V 1. 751 27. 8 T =25. 8

' s5=4. 19 -R -53. VI 1. 751 27. 8 Tu=2. 50

R z=Plano 7. A lens having an equivalent focal length of mm.

are'numbered from the front, N is the index of refraction for the D lineof the spectrum, V is the index of dispersion, and R, T and S referrespectively to the radii of curvature of the lens surfaces, the axialthicknesses of the lens elements and the axial spacings between the lenselements, numbered by subscript from front to rear:

8. A six element Petzval type lens having an equivalent focal length of100 mm. comprising from front to rear,

Thicknesses and a first airspaced doublet consisting of a front biconvexele- Lens N, v Radil (mm.) spacings (mm.) ment and a rear biconcaveelement, a simple biconvex ele- 5 ment, a second positive airspaceddoublet consisting ofra. I L611 5&3 TF2 front positive element and arear biconcave element, and

Rig-82M SF) 6 a negative field flattening element behind the secondRz=-147-1 doublet, the elements having characteristics substantially II1.720 29.3 T2=11.4 10

R4=1612 S 63 2 within the following ranges of values m which the lens0.19 elements are numbered from the front, N is the index of m 517refraction for the D line of the spectrum, V is the index Rpm 31:23? ofdispersion and R, T and S refer respectively to the IV 697 2 RB= 442 915 radii of curvature of the lens surfaces, the axial thicknesses R 1896 4= of the lens-elements and the axial spacings between the 0= 1 v1.751 27.3 R 1926 T,=20.0 lens elements, numbered by subscnpt from frontto rear:

S5=3.14 RIF-71.00 20 VI 1.751 27.8 T5=3.64

Lens Thlcknesses and N, V Radii (mm.) spacings (mm.)

. R1=96.13to 114.3 r 1.611 to 1.713 53.3 to 58.3 'r.=22.7 to 28.6

. Rz=762.5 to -1120 s1=11.5 to 19.7 R1=-137.1 to -154.3 II 1.072 to1.728 28.3 to 32.2 'm=11.4 to 22.2

. R4=232 to 1012 s1=41.5 to 03.2 R.=51.24m00.13 III 1.51010 1.517 64.0to 64.5 '1;=25.4 to 33.7

R0=196.0 to -325.1

- 1 s3=1.79 to 2.33 R7=61.42 to 74.10 IV 1.611 to 1.713 53.8 to 58.8T4=8.82 to 13.0

Rg=+18l6 to -2s45 s.=1.0s to 2.22 Ro=145.4 to -1s9.0 v 1.717 to 1.75527.5 to 29.5 T5=22.5 to 33.4 R =192.6 to 340.5 p I s,=3.14 to 5.05RIF-50.70 to -71.00 W 1.717 to 1.755 27.5 to 29.5 T.=2.50 to 3.54

References Cited UNITED STATES PATENTS 2,685,229 8/1954 Schultz et a].350214 3,320,016 5/ 1967 Van- Graafeiland 350-215 FOREIGN PATENTS536,448 5/1941 Great Britain.

DAVID SCHONBERG, Primary Examiner P. A. SACHER, Assistant Examiner US.01. X.R.

